The present invention relates to a leukocyte separator and a method of manufacturing the same, and more particularly to a leukocyte separator having a high and stable trapping capability for trapping leukocytes without the danger of discharging foreign material and a method of manufacturing such a leukocyte separator.
Forms of blood transfusion range from conventional whole blood transfusion to component transfusion that is widely relied upon recently by which only a blood component required by a patient is transfused to the patient. In the component transfusion, it is important that desired blood portions or components be separated highly purely from the blood of a donor.
More specifically, various blood components such as concentrated red cells (CRC), a plasma concentrate (PC), and platelet poor plasma (PPP) are separated from collected or donated blood by a centrifugal separation process. Concentrated red cells thus separated are widely used as a component preparation in administering red cells to patients who need them. Heretofore, concentrated red cells contain many leukocytes and platelets, which should be removed as much as possible. Various efforts have been made for the removal of leukocytes and platelets from donated blood.
A variety of methods are known for increasing the purity of red cell preparations. Such methods include a gravitational and centrifugal separating method utilizing different specific gravities of blood cells, a method using a trapping material for trapping blood cells by sticking, adhesion, or the like, and a method of separating leukocytes by using a red cell coagulant. Among these methods, the method using a trapping material is widely used since it has a high efficiency for leukocytal removal and is easy to carry out. Typical trapping materials include very short fibers such as natural cellulose fibers, polyester fibers, polyamide fibers, polyacrylonitrile fibers, glass fibers, or the like, which are packed in a column, or fabricated into nonwoven fabric.
Where fibers are packed in a column, it is quite difficult, tedious, and time-consuming to fill the fibers uniformly in the column. Dependent on how the fibers are packed, channeling may occur while the trapping material is being handled for purifying red cell preparations. If the fibers are packed in a high density for sufficiently trapping leukocytes, the time required for filtering the blood through the trapping material becomes very long. Some of the packed fibers may flow out of the column during usage since the fibers are not usually intertwined sufficiently. These problems are not liable to occur with those fibers which are fabricated into nonwoven fabric. However, it has been pointed out that a nonwoven fabric used as a trapping material is apt to get easily clogged by blood cells trapped by the fabric.